Angioplasty is a procedure widely used for the treatment of blocked arteries and has been developed to the point where it is effective for blockages varying considerably in density, size and location in the vasculature, and has also been used in combination with other procedures. With such a wide scope of applicability, a considerable amount of variation can be encountered in terms of the therapeutic needs for treating a blockage and any conditions associated with it, as well as the means of meeting those needs. For example, the ease of placing the balloon tip of the catheter at the desired location, the size and type of balloon needed, the need for other means of ablating the blockage or otherwise treating the vessel, can all vary widely, and it is frequently impossible to accurately predict each of these in advance of the procedure. As a result, the physician must often exchange a guidewire or balloon after it has been inserted.
Over-the-wire catheters are designed to permit these types of exchanges. Due to the distance that the catheter must be inserted inside the body to reach the site where treatment is to be performed, however, these catheters are generally about 135 cm or more in length. While drawing the catheter backward over the guidewire, of course, the physician must maintain a grip on the guidewire to hold its position. As a result, the guidewire will generally be at least twice as long as the catheter. Alternatively, a guidewire of shorter length, but one to which an extension can be attached, will be used. In either case, the procedure is awkward, the extra length or the extension interfering with the ease and speed of the exchange and of the procedure as a whole.